The System and Method for Gas Recognition by Analysis of Bispectrum Functions generally relates to chemical analyte detection and identification, and more particularly, to a system and method of chemical analyte detection and identification by analysis of resistance fluctuations of a Metal Oxide Semiconductor (MOS) gas sensor.
Homeland defense, including anti-terrorist efforts require highly selective, sensitive, and reliable detection of harmful agents. Intensive research has resulted in the use of chemical and biological sensor elements for the development of systems known as electronic noses (for gas and odor sensing) and electronic tongues (for fluid sensing).
One way of gas sensing is based on Metal Oxide Semiconductor (MOS) gas sensors. These devices generally operate by measuring the change in resistance between electrode pairs as a result of the interaction between the surface of the metal-oxide semiconductor and the ambient gas. As gas molecules are adsorbed and desorbed by the MOS sensor, the resistance of the sensor changes. Traditionally, only the DC (average) resistance is measured. The DC resistance is a single value that cannot be used as a pattern for recognition of different gases.
More recently, the power spectral density of fluctuations in the resistance of the MOS sensor have been measured. This power spectral density can be used to generate a pattern to identify different gases by giving information about power of the stochastic component at different frequencies. However, the power spectral density looses information about the phase relationships of the resistance fluctuations.
Therefore, it can be appreciated that a sensitive and reliable method of MOS sensor analysis that preserves phase relationships of resistance fluctuations is needed.